Larger than a t-rex and able to catch fish the size of bison. This ferocious predator from the cretaceous is one of the most mysterious and controversial dinosaurs to ever live. Its secrets are only starting to be uncovered. This is the spinosaurus. Today we’re delving into dangerous Cretaceous waters and discussing one of the biggest bones of contention in the Dino world.
What did spinosaurus actually look like?
The story of Spinosaurus starts in 1915 when a German paleontologist named Ernst Stromer discovered the fossils of a theropod with very narrow 1.6 meters long lower jaws and long spines coming out of its backbone.
Wanting to be as descriptive as possible, he named it spinosaurus and sent the fossils to the Bavarian State Collection of Paleontology in Munich, where it was estimated to be about 97 myo. But during World War 2, the fossils were destroyed during a bombing of the city. For decades, illustrations of these few bones were all we had, so paleoartists imagined it as a 16-meter long t-rex with a croc-like face, and a back sail. Basically the coolest dino of all the time. This was the last time we had a unified vision of this dino and everyone was happy. But then more fossils started popping up, and the paleo community started forming factions.
In the 1980s, a new similar species was discovered. It was called the baryonyx, it had huge claws, and showed that these were part of a family of dinosaurs, which was then named the spinosauridae. These related species helped scientists piece together what spinos looked like a little better and cemented its place as the largest theropod ever known.
The long snout suggested a fish-heavy diet, and the huge claws would have helped it grab prey close to the shore. Fortunately, or maybe unfortunately, we kept finding fossils, which contradicted our early perceptions of spinos. Its like reading a book in reverse and understanding less and less as the pages turn.
First of all, their hind legs were revealed to be extremely short compared to other theropods like T-rex. They would make spinos awkward and slow walkers, but might have been an adaptation for life in the water. They could have helped it swim like a crocodilian, and since they already had a croc-like face and likely ate fish, it would have made sense to spend more time in the water than other dinos. And the bones were also more dense than in other theropods, which in other animals is used for buoyancy control.
This is a bigger deal than it sounds like. Up until that point there had been no indications of aquatic dinosaurs. Other aquatic creatures of the time like the plesiosaurs and mosasaurs are technically not dinosaurs. It was weird! But then, tail vertebrae were found. The tail was revealed to be long, narrow, and flat, like the tail of an axolotl which would have helped spinosaurus propel itself in the water. Long and strong toe bones, similar to those found in modern shorebirds, suggested they have the ability to walk in muddy or silty soil.
They could have even been webbed, but unfortunately, we have no evidence of that. There is also evidence that they had pressure receptors along the snout, much like crocodilians. And then, the discovery of a large number of teeth in river environments suggested they could have spent a lot of time, maybe all of their time in the water.
Of course, that would have been way too easy a conclusion to this debate. Evidence for a more land-based lifestyle also started mounting. Body reconstructions suggested it couldn’t really stand upright in the water without tipping over unless it was moving forward. The tail also seemed too weak to be used for propulsion as effectively as a crocodilian does. It would also have been too massive and too awkward a swimmer to pursue prey underwater.
The sail and tail may not have been for balance and propulsion respectively, but rather, a display for sexual selection, like a peacock’s tail. Or it could have been a structure for a thermoregulatory organ like elephant ears, or maybe even fat deposits, like a bison’s hump. So depending on how you see it, it could have been an aquatic predator behaviourally similar to a croc, or a wading predator, like a grizzly bear, who specialized in fish but could venture to land and eat carrion or catch prey opportunistically.
The whole issue is complicated by the fact that only 6 specimens have ever been found, and they all have been incomplete and of different ages and sizes. Making an accurate model has been difficult, kinda like solving a 1000-piece jigsaw puzzle, but you only have 6 pieces. Every sail vertebra ever found is broken and we don’t even know how long they were or if they created an arc or an M-shaped structure or what its purpose was. We don’t know how powerful and propulsive the tail was.
We don’t know if when it walked on land it moved like a bear with the ability to stand on its hind legs, or more like a pangolin, using its tail to balance while walking on two feet. We don’t know how good of a swimmer it was. But we do know it liked to eat fish, and spend a lot of time near the water fishing. We know it was huge and, more importantly, that it was one of the coolest animals to ever live.
So please, if you’re out there looking for fossils in the deserts of northern Africa, we need you to help us get closer to solving this puzzle! Until then, it will continue to cause fights on paleo-subreddits, provoke academic beefs, and break up families of paleontologists.
What do YOU think it looked like based on the evidence?
My favorite thing about it, is there’s still so much room for interpretation. Let us know in the comments below.
Thanks for reading this post. See ya!